PO 400 Filter not working

Hi, I’ve just put together the PO Modular 400. I can get sound when I do the first couple of patches in the manual.
The Square, Saw and Sine modules seem to work fine.
Mixer works, LFO works.
I tried doing the patch in https://teenage.engineering/guides/po-modular/400
2.2 A Simple Mono Synth.
The first part is supposed to produce a sound, but doesn’t. I’ve adjusted all the knobs.
I’ve opened the case back up to make sure it was properly connected to the power rail. I changed which port on the power rail it was connected to.

Any suggestions?

Playing about further. I’ve continued the instructions and plugged in the sequencer to the Envelope, and the Env to the VCA.
Now I’m getting a drum rythm. No musical notes though.

Did you try the filter module alone with one oscillator ? Connect one of the oscillator to the speaker first. Turn the pitch knob on the oscillator until you hear an audible sound. Then add the filter between the oscillator and speaker and turn the cutoff knob, you should hear something, if not, it’s not working properly.

It could also be the enveloppe with attack or decay knob turned all the way down, so try to turn up the A and D on the envelope module.

I just put together my 400 tonight. My filter isn’t working either. It only works when control is sent.

I ran into the same problem,It only works when control is sent.This makes me very anxious,Did you solve it?

It’s the way the filter module works. You need to patch one of the control inputs.

Hi, I got mine working.
I took the filter module out and on the face of the circuit board are a couple of tiny potentiometers.
Use a small screwdriver and adjust them (I did this with everything hooked up so I could fiddle with the main knobs). Did the job.

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Thank you for the reply! Can you be more specific with the way you adjust?

I feel that the manual on the official website has not been updated

TE sent me a new filter. I ended up selling my 400. Didn’t love it.

I contacted the seller today, and I hope to change one for me

Hopefully this picture will be enough.
Take the filter out and between the left Level knob and Control jack socket there are 2 tiny potentiometers that can be adjusted with a crosshead screwdriver.
Plug everything thing and patch it using the Corpus Squentia example in the manual (a bit awkward).
You want to set the tiny potentiometers so that when you adjust the main knobs they produce sounds at either extreme. I didn’t quite get that, but I was pleased that the filter was having an effect at all.

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Wow, thank you very much, I will try it after get off work today. Yesterday, I also reported the problem to TE and the seller, but there is no answer to me at present. Many thanks !!! :slight_smile: